#include<iostream>
using namespace std;
int main( )
 {
    int n; double y;
    cout<<"n="; cin>>n;
    if(n<=0) y=0;
    else
      if(n<=5) y=1.0;
      else
        if(n<=10) y=1.5; 
          else y=2.0;
    cout<<y;
    return 0;
 }
 